Duplicate children! Attach and detach isn't helping can you?

Duplicate children! Attach and detach isn't helping can you?

I have recently uploaded a new gedcom to FTMM and have been trying to clean up any errors etc. I've noticed that I seem to have duplicates of people where they are married in some instances but in others the wife disappears. I've tried to detach and attach but lose people and whole branches so then have to re-attach them. I've tried searching for duplicates but is says it can't find any which leaves me to think that these aren't duplicates but something i've done.

Does anyone have a similar problem that they've discovered the answer for? Is there another tool which would help me see where these hidden people come from?